#include <stdio.h>

#define max(a, b) ((a) > (b) ? (a) : (b))
#define exchange(t, a, b) { t mid = a; a = b; b = mid; }

int main() {
	int a = 5, b = 6;

	printf("max number: %d\n", max(a, b));
	exchange(int, a, b);
	printf("exchange a and b, a: %d, b: %d\n", a, b);

	return 0;
}